Joe and angie are studying how listening to music affects grades. joe listened to music while he studied while angie studied in silence. after two weeks, they took the same math test and joe scored higher than angie. they came to the conclusion that listening to music will improve grades. what comment would you make to joe and angie about their experiment? select one: a. they should have tested more people. b. joe was already better at math than angie. c. this topic has already been studied before. d. they should have chosen a different subject besides math.